1. Field of the Invention
This invention relates to pump engineering, primarily to well jet devices used for well logging and to methods of operating thereof.
2. Background Art
A well jet device is known that comprises a pipe string with a jet pump and a packer with the possibility of pumping a working medium through the jet pump (RU 2059891 C1).
The same source teaches a method of operating a well jet device, comprising arranging a jet pump on a pipe string in a well and a geophysical instrument installed below the jet pump in a flow string, lowering the pipe string with the jet pump, the packer and the geophysical instrument into a well and pumping a liquid working medium through the jet pump.
These known well jet device and the operating method thereof enable to pump a variety of produced media, e.g., oil, from wells, while simultaneously treating the produced medium and the near-well area of a formation.
However, working capabilities of the known device and method are limited in studying wells that narrows their application in a number of cases.
The closest to this invention as to the technical essence and the achieved result is a well jet device comprising a pipe string, a packer and a jet pump in the body of which an active nozzle with a mixing chamber is installed and a pass-through channel with a mounting seat for installing a sealing unit with an axial channel is made, the jet pump output being connected to the pipe string above the sealing unit, the entry of a channel for supplying a pumped-out medium to the jet pump being connected to the pipe string below the sealing unit, and the entry of a channel for supplying a working medium to the active nozzle being connected to space surrounding a flow string, and several channels for supplying a pumped out medium being made in the jet pump body (RU 2106540 C1).
The same patent teaches a method of operating a well jet device, comprising arranging a packer and a jet pump on a pipe string in a well, the packer being installed above a producing formation, lowering a sealing unit and a well-logging instrument on a cable, and pumping an active working medium, e.g., water, along the pipe string annular space to the jet pump nozzle, thus reducing pressure in an under-packer area and creating a pressure drawdown on the formation, monitoring parameters of the pumped-out formation fluid when the jet pump is operated, and equalizing pressures along the jet pump flow channel by flowing a fluid through the jet pump flow channel after stopping supplying the active working medium.
These device and operating method thereof enable to carry out various technological operations in a well below the level at which the jet pump is installed, including those involving reducing pressure differential above and under the sealing unit.
However, this device does not enable to utilize its capabilities in full due to the fact that it is impossible to maintain pressure drawdown on a formation when the jet pump is not operated, which does not enable to study wells in full.